package org.apache.ddlutils.platform.db2;

        /*
         * Licensed to the Apache Software Foundation (ASF) under one
         * or more contributor license agreements.  See the NOTICE file
         * distributed with this work for additional information
         * regarding copyright ownership.  The ASF licenses this file
         * to you under the Apache License, Version 2.0 (the
         * "License"); you may not use this file except in compliance
         * with the License.  You may obtain a copy of the License at
         *
         *   http://www.apache.org/licenses/LICENSE-2.0
         *
         * Unless required by applicable law or agreed to in writing,
         * software distributed under the License is distributed on an
         * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
         * KIND, either express or implied.  See the License for the
         * specific language governing permissions and limitations
         * under the License.
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import org.apache.ddlutils.DdlUtilsException;
import org.apache.ddlutils.Platform;
import org.apache.ddlutils.model.Column;
import org.apache.ddlutils.model.Index;
import org.apache.ddlutils.model.Table;
import org.apache.ddlutils.model.TypeMap;
import org.apache.ddlutils.platform.DatabaseMetaDataWrapper;
import org.apache.ddlutils.platform.JdbcModelReader;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.HashSet;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * Reads a database model from a Db2 UDB database.
 *
 * @version $Revision: $
 */
public class Db2ModelReader extends JdbcModelReader {
    /**
     * Known system tables that Db2 creates (e.g. automatic maintenance).
     */
    private static final String[] KNOWN_SYSTEM_TABLES = {"STMG_DBSIZE_INFO", "HMON_ATM_INFO", "HMON_COLLECTION", "POLICY"};
    /**
     * The regular expression pattern for the time values that Db2 returns.
     */
    private Pattern _db2TimePattern;
    /**
     * The regular expression pattern for the timestamp values that Db2 returns.
     */
    private Pattern _db2TimestampPattern;

    /**
     * Creates a new model reader for Db2 databases.
     *
     * @param platform The platform that this model reader belongs to
     */
    public Db2ModelReader(Platform platform) {
        super(platform);
        setDefaultCatalogPattern(null);
        setDefaultSchemaPattern(null);

        try {
            _db2TimePattern = Pattern.compile("'(\\d{2}).(\\d{2}).(\\d{2})'");
            _db2TimestampPattern = Pattern.compile("'(\\d{4}\\-\\d{2}\\-\\d{2})\\-(\\d{2}).(\\d{2}).(\\d{2})(\\.\\d{1,8})?'");
        } catch (PatternSyntaxException ex) {
            throw new DdlUtilsException(ex);
        }
    }

    /**
     * {@inheritDoc}
     */
    protected Table readTable(DatabaseMetaDataWrapper metaData, Map values) throws SQLException {
        String tableName = (String) values.get("TABLE_NAME");

        for (int idx = 0; idx < KNOWN_SYSTEM_TABLES.length; idx++) {
            if (KNOWN_SYSTEM_TABLES[idx].equals(tableName)) {
                return null;
            }
        }

        Table table = super.readTable(metaData, values);

        if (table != null) {
            // Db2 does not return the auto-increment status via the database metadata
            determineAutoIncrementColumns(table);
        }
        return table;
    }

    /**
     * {@inheritDoc}
     */
    protected Column readColumn(DatabaseMetaDataWrapper metaData, Map values) throws SQLException {
        Column column = super.readColumn(metaData, values);

        if (column.getDefaultValue() != null) {
            if (column.getTypeCode() == Types.TIME) {
                Matcher matcher = _db2TimePattern.matcher(column.getDefaultValue());

                // Db2 returns "HH24.MI.SS"
                if (matcher.matches()) {
                    StringBuffer newDefault = new StringBuffer();

                    newDefault.append("'");
                    // the hour
                    newDefault.append(matcher.group(1));
                    newDefault.append(":");
                    // the minute
                    newDefault.append(matcher.group(2));
                    newDefault.append(":");
                    // the second
                    newDefault.append(matcher.group(3));
                    newDefault.append("'");

                    column.setDefaultValue(newDefault.toString());
                }
            } else if (column.getTypeCode() == Types.TIMESTAMP) {
                Matcher matcher = _db2TimestampPattern.matcher(column.getDefaultValue());

                // Db2 returns "YYYY-MM-DD-HH24.MI.SS.FF"
                if (matcher.matches()) {
                    StringBuffer newDefault = new StringBuffer();

                    newDefault.append("'");
                    // group 1 is the date which has the correct format
                    newDefault.append(matcher.group(1));
                    newDefault.append(" ");
                    // the hour
                    newDefault.append(matcher.group(2));
                    newDefault.append(":");
                    // the minute
                    newDefault.append(matcher.group(3));
                    newDefault.append(":");
                    // the second
                    newDefault.append(matcher.group(4));
                    // optionally, the fraction
                    if ((matcher.groupCount() >= 5) && (matcher.group(5) != null)) {
                        newDefault.append(matcher.group(5));
                    }
                    newDefault.append("'");

                    column.setDefaultValue(newDefault.toString());
                }
            } else if (TypeMap.isTextType(column.getTypeCode())) {
                column.setDefaultValue(unescape(column.getDefaultValue(), "'", "''"));
            }
        }
        return column;
    }

    /**
     * Helper method that determines the auto increment status using Firebird's system tables.
     *
     * @param table The table
     */
    protected void determineAutoIncrementColumns(Table table) throws SQLException {
        final String query = "SELECT COLNAME FROM SYSCAT.COLUMNS WHERE TABNAME = ? AND IDENTITY = 'Y' AND HIDDEN != 'S'";

        PreparedStatement stmt = null;

        try {
            stmt = getConnection().prepareStatement(query);
            stmt.setString(1, table.getName());

            ResultSet rs = stmt.executeQuery();

            while (rs.next()) {
                String colName = rs.getString(1).trim();
                Column column = table.findColumn(colName, getPlatform().isDelimitedIdentifierModeOn());

                if (column != null) {
                    column.setAutoIncrement(true);
                }
            }
        } finally {
            closeStatement(stmt);
        }
    }

    /**
     * {@inheritDoc}
     */
    protected boolean isInternalPrimaryKeyIndex(DatabaseMetaDataWrapper metaData, Table table, Index index) throws SQLException {
        // Db2 uses the form "SQL060205225246220" if the primary key was defined during table creation
        // When the ALTER TABLE way was used however, the index has the name of the primary key
        if (index.getName().startsWith("SQL")) {
            try {
                Long.parseLong(index.getName().substring(3));
                return true;
            } catch (NumberFormatException ex) {
                // we ignore it
            }
            return false;
        } else {
            // we'll compare the index name to the names of all primary keys
            // TODO: Once primary key names are supported, this can be done easier via the table object
            ResultSet pkData = null;
            HashSet pkNames = new HashSet();

            try {
                pkData = metaData.getPrimaryKeys(metaData.escapeForSearch(table.getName()));
                while (pkData.next()) {
                    Map values = readColumns(pkData, getColumnsForPK());

                    pkNames.add(values.get("PK_NAME"));
                }
            } finally {
                closeResultSet(pkData);
            }

            return pkNames.contains(index.getName());
        }
    }
}
